The present invention relates generally to data routing systems, and more particularly to methods and apparatus for providing secure communications on a network.
A packet switch communication system includes a network of one or more switches or routers connecting a plurality of users. A packet is the fundamental unit of transfer in the packet switch communication system. A user can be an individual user terminal or another network.
A layer 2 (L2) switch is a switching device which receives packets containing data or control information on one port, and based on a media access connection (MAC) address contained within the packet, switches the packet out another port. Conventional L2 switches perform this switching function by evaluating layer 2 (L2) header information contained within the packet in order to determine the proper output port for a particular packet. The L2 switch includes a table that maps MAC addresses with output ports. If a MAC address is unknown (i.e., there is no corresponding entry in the table), then the corresponding packet is broadcast to all output ports with the hope that another component in the packet switched communication system will recognize the MAC address (and pass back information to the forwarding L2 switch to update its table). Other types of L2 devices include bridges.
A router is a switching device which receives packets containing data or control information on one port, and based on destination information contained within the packet, routes the packet to a next hop to/toward the destination. Conventional routers perform this switching function by evaluating layer 3 (L3) header information contained within the packet in order to determine a next hop for a particular packet. The layer 3 information includes an IP address associated with the intended destination (as well as source address) for the packet.
The network coupling the users can be an intranet, that is, a network connecting one or more private servers such as a local area network (LAN). Alternatively, the network can be a public network, such as the Internet, in which data packets are passed over untrusted communication links. The network configuration can include a combination of public and private networks. For example, two or more LAN's with individual terminals can be coupled together using a public network such as the Internet. Data security issues can arise when public and private networks are linked or when distinct networks are coupled. For example, conventional packet switched communication systems that include links between public and private networks typically include security measures for assuring network access control and data integrity.
In order to assure individual packet security, packet switched communication systems can include encryption/decryption services. Prior to leaving a trusted network (or portion of a network), individual packets can be encrypted to minimize the possibility of data loss while the packet is transferred over an untrusted (e.g., public) network (or portion thereof). Upon receipt at a destination or another trusted portion of the communication system (e.g., at a firewall just before the destination), the packet can be decrypted and subsequently delivered to its intended destination. The use of encryption and decryption allows for the creation of a virtual private network (VPN) between users separated by untrusted communication links.
In addition to security concerns for the data transferred over the public portion of the communications system, the private portions of the network must safeguard against intrusions through the gateway provided at the interface of the private and the public networks. A firewall is a device that can be coupled in-line between a public network and private network for screening packets received from the public network. A firewall is a particular type of L3/L4 device that can be used to enforce policy and filtering functions. A firewall can include one or more engines for inspecting, filtering, authenticating, encrypting, decrypting and otherwise manipulating received packets. Conventional firewalls use L3 and L4 header information including IP addresses associated with the source and destination of a given packet being processed. Received packets are inspected and thereafter forwarded or dropped in accordance with the policies associated with the given domain.